hello sswapp. spray some gunk engine bright straight down behind the drivers side head and let it soak for a while. then spray it off with your garden hose[watch your eyes] and look down there with a small but strong flashlight. if you use bi-focals like me this is not easy ,but it is possible to see the numbers on most vehicles. you might also have a real thick buildup in which case you will have to use a thin , long handled brush down there to expose the numbers.i have also used a small mirror and a strong light to see down in between the firewall and the engine, only trouble is the numbers are backwards when you finally find them.good luck
